Substances which conduct electricity have been divided into two main classes. Those with conductivities of 10.sup.-9 to 10.sup.2 S/cm (S = Siemen = Ohm.sup.-1 are called semiconductive or electroactive. Materials with conductivities of 10.sup.2 S/cm and higher are called conductive. A number of polymers exhibit conductivities in or approaching the latter range, particularly when doped with oxidizing or reducing agents. Examples of these are polyaniline, polypyrrole, polythiophene, and polyacetylene.
These polymers are potentially useful in batteries, as a lightweight replacement for metal wire, and in antistatic applications as well as in shielding from radio frequencies and electromagnetism.
Polypyrrole has a conductivity of 10.sup.2 S/cm. This polymer unfortunately has the disadvantage of being extremely brittle, and is generally considered to be unprocessable. Therefore, it has limited utility. It has been disclosed that polypyrrole can be coated onto textiles to provide conductive textiles. (R. V. Gregory, W. C. Kimbrell and H. H. Kuhn, Abstracts, International Conference on Synthetic Metals, Santa Fe, New Mexico (1988)). Of course textile films generally cannot be processed, for example, by extrusion. Polypyrrole has also been coated onto submicronic latex particles. (A. Yassar, J. Roncali and F. Garnier, Polym. Commun., 28, 103 (1987)). The conductivity of films formed from these products is relatively low reaching no higher than 0.25 S/cm.
Japanese Kokai 61-111325 discloses polymer particles coated with in situ formed conductive polymers such as polypyrrole, polyaniline, and polythiophene. These composites, which contain relatively high percentages (38-60 wt. %) of the conductive polymer are relatively brittle and unsuitable for most applications. Further, this reference fails to make any disclosure of particle size or shape.